From "The Traditional Irish Wedding", an excellent book all about Irish Weddings by Bridget Haggerty, here are a few superstitions that portend good luck for the marriage:
• A fine day means good luck, especially if the sun shone on the bride
• A man should always be the first to wish joy to the bride, never a woman
• To hear a cuckoo or to see three magpies on the wedding morning was lucky
• The wedding party should always take the longest road home from the church
• It was said to be lucky if you married during a "growing moon and a flowing tide"
• When leaving the church, someone must throw an old shoe over the bride's head so she will have good luck
• If the bride's mother-in-law breaks a piece of wedding cake on the bride's head as she enters the house after the ceremony, they will be friends for life.
And as for selecting the day of the week for the wedding:
Monday for health,
Tuesday for wealth,
Wednesday the best day of all,
Thursday for losses,
Friday for crosses and
Saturday no day at all.
Happy St. Patrick's Day!